1. Field of the Invention
The present invention relates to a substrate processing apparatus for dipping a thin plate-like substrate (hereinafter referred to simply as "substrate"), such as a semiconductor wafer and a glass plate for a liquid crystal display, into a processing liquid and for performing various types of processing, such as cleaning, on a surface of the substrate.
2. Description of the Prior Art
Conventional substrate processing apparatuses include a multiple-bath type processing apparatus for dipping a substrate sequentially into a plurality of processing baths each having only one function and for performing a series of treatments on the substrate, and a single-bath type processing apparatus for performing a series of treatments on a substrate which is put into only one bath which performs multiple functions while sequentially filling the bath with a processing liquid such as a chemical liquid and deionized water.
More specifically, the former multiple-bath type processing apparatus comprises one or more chemical processing baths for processing a substrate using one type of chemical liquid and one or more water cleaning baths. Through a plurality of steps of dipping a substrate sequentially into these baths in a predetermined order, contaminants at a surface of the substrate are removed, an oxide film at the surface of the substrate is etched, a resist film is removed, etc.
While a transport robot is used to transport a substrate sequentially to the respective baths during such steps, since a handling part of the transport robot holds a substrate which has just been processed with a chemical liquid or water, water or the chemical liquid adheres to the handling part. To deal with this, the substrate processing apparatus as described above comprises an exclusive cleaning part for cleaning and drying the handling part carrying water or the chemical liquid after a substrate is transferred.
On the other hand, the latter single-bath type processing apparatus comprises only one processing bath which is capable of performing both processing using a chemical liquid and cleaning with water. A chemical liquid and deionized water are alternately supplied in a predetermined order while holding a substrate within this only one processing bath, whereby contaminants at a surface of the substrate are removed, an oxide film at the surface of the substrate is etched, a resist film is removed, etc.
However, since transportation of a substrate from one bath to another is essential to the former apparatus, insufficient cleaning is likely to occur such as adhesion of particles and growth of an unnecessary film. Further, since it is necessary to dispose a number of processing baths, the size of the entire substrate processing apparatus inevitably increases.
In addition, since the former apparatus comprises the exclusive cleaning part for cleaning and drying the handling part of the transport robot, a foot space of the substrate processing apparatus increases. Further, since the former apparatus frequently requires the step of cleaning and drying the handling part, a throughput during processing of a substrate degrades. Still further, in the case of such an apparatus which directly holds a plurality of substrates with the handling part for simultaneous processing of the plurality of substrates, or in the case of such an apparatus which houses a plurality of substrates into a carrier and holds the carrier, it is difficult to perfectly clean and dry the handling part, and therefore, the substrates are likely to get contaminated by chemical liquid, etc. remaining on the handling port Beside, in the case of such an apparatus in which a lifter is disposed to each processing bath and a substrate is held inside and outside each processing bath, since the transport robot does not include a vertical movement mechanism and it is therefore necessary to dispose a mechanism for vertically moving the exclusive cleaning part for the handling part, the structure of the exclusive cleaning part becomes complex.
Meanwhile, although the latter apparatus does not have such problems as above with the former apparatus, since a step of replacing a chemical liquid within a bath with deionized water and thereafter replacing deionized water with other chemical liquid is essential in the latter apparatus, it takes time to adjust a temperature and hence a throughput becomes extremely low during processing which requires to use a chemical liquid at a high temperature or processing which requires to use a chemical liquid which demands fine adjustment of a temperature. Further, it takes time to adjust the density of a chemical liquid within a bath to a predetermined density and hence a throughput becomes extremely low during processing which requires to use a chemical liquid which has a high density.